Secondary air feeding fire door for boilers, furnaces, and the like



y 1954 M. STEUERMAN 3,

SECONDARY AIR FEEDING FIRE DOOR FOR BOILERS, FURNACES, AND THE LIKE Filed July 1, 1949 3 Sheets-Sheet l F/GJ m Inventor MAREK STEUERMAN Attorney y 1954 M. STEUERMAN 2,683,429 SECONDARY AIR FEEDING FIRE DOOR FOR BOILERS, FURNACES, AND THE LIKE 3 Sheets-Sheet 2 Filed July 1, 1949 wi l/1x14711111:

MAR K STEUERMAN Attorney July 13, 1954 Filed July 1, 1949 M. ISTEUERMAN 2,683,429

SECONDARY AIR FEEDING FIRE DOOR FOR BOILERS, FURNACES, AND THE LIKE 5 Sheets-Sheet 3 Inventor MAREK STEU ERMAN Attorney Patented July 13, 1954 UNITED STATES amaze SEGONDARY AIR FEEDING FIRE DOOR FOR- .BOILERS, FURNACES, AND THE LIKE 4 Claims.

This invention concerns improvements in or relating to fire doors for boilers, furnaces and the like, and has especial reference to fire doors constructed so as to provide at least one, and preferably two or more, controlled supplies of secondary air.

Many forms of smoke eliminator or reducer and/or fuel economiser are known, the purpose of these devices (hereinafter referred to as smoke eliminators) being to-provide secondary air to the boiler, furnace, or the like (all hereinafter included in the term furnace) on the upper side of the fuel bed.

The secondary air has the effect of reducing or eliminating the smoke emitted and also effects an economy of fuel.

It is now well recognised that the efficiency of a furnace is reduced in accordance with the weight of solid matter passing in the form of smoke to the chimney of the furnace and that the elimination of this smoke can efiect a very considerable economy in the fuel consumption of the furnace as well as avoiding atmospheric pollution.

The secondary air is supplied to the upper side of the fuel bed to bring about the combustion in the furnace of the combustible vapours and gases emanating from the bituminous coal on the fire bed, it being found that Where the fire bed is more than four inches thick inadequate quantities of air pass through the fire bed from the underside of the grate to effect proper combustion of the volatile matter above the fire bed, and the aim of smoke eliminators should be to supply a quantity of secondary air during the operation of the furnace at a rate proportionate to that at which combustible volatile matter or gases are evolved from the fire bed.

Among the smoke eliminators hitherto proposed are those which are either fitted to the inside of the existing furnace door, or which are formed as part of the said door, these smoke eliminators usually being in the form of a hollow box, with or without baifie means therein, and having an inlet or inlets on the outer side of the furnace door to admit secondary air to the hollow box-like structure Where this air is preheated and then delivered to the upper side of the furnace bed.

This invention is concerned with smoke eliminators forming a part of the furnace door as distinct from those which are merely bolted or similarly fixed to the inside of an existing furnace door.

A The door openings of different types of furnaces vary in size and shape and an object of the present invention is to provide means whereby a smoke eliminator of a standard size and pattern in which are provided the necessary means for controlling the secondary air supply, and hereinafter called a standard secondary air supply unit, can be utilised satisfactorily on many types of boiler and furnace irrespective of the said variations in the sizes and shapes of their door openings.

According to the invention there is provided for a boiler or furnace a standard secondary air supply unit which is less in area than the door opening of such boiler or furnace, and a frame or base plate having an opening in which the said standard unit is adapted to be fitted, the exterior dimensions of the said frame or base plate being such as to suit the said door opening.

It will be appreciated that although the size and form of the standard secondary air supply unit always remains the same for a given range of door opening sizes and forms, a different frame or base plate will be provided for each different size and shape of door opening.

Alternatively a standard form of frame or base plate could be provided in which the external dimensions exceed those of any door opening to which the standard secondary air supply unit is to be fitted and such frames or base plates could subsequently be peripherally modified to suit any particular door opening.

Preferably the hinge and fastening means for the door will be provided on the said frame or base plate.

The form of the opening in the said frame or base plate and the peripheral form of the standard secondary air supply unit are preferably matched so that these parts fit accurately together. Moreover, either the said standard unit or the frame or base plate may have lugs or retaining plates adapted to overlie the other of these parts for fixing the parts together by means of, for example, bolts or studs.

The standard unit may project beyond either side of both sides of the frame or base plate when fitted thereto and the frame or base plate will preferably completely surround the said unit.

Thus according to a further aspect of the invention there is provided in combination a series of frame or base plates all having different external dimensions and/or shapes but all having an opening of a common size and shape, and a standard secondary air supply unit adapted for fitting into the opening of any one of said frames or base plates, whereby a fire door can be provided to suit any particular door opening by assembling together the said standard and appropriate frame or base plate selected from the senes.

Preferably the standard unit is made as an iron casting and may be all in once piece, or in two or more parts. Also the said frame or base plate may be an iron casting.

In order that the nature of the invention may be more readily understood and carried into practice, one embodiment of the same will now be described by way of example with reference to the accompanying drawings, in which:

Figure l is a front elevation of the fire door of a Lancashire boiler and a small part of the front of the boiler, the said fire door being constructed in accordance with this invention;

Figure 2 is an inside or rear view of the fire door shown in Figure 1;

Figure 3 is a vertical section on line III-III of Figure 1;

Figure 4 is a horizontal section on line IV--IV of Figure 3; and

Figure 5 is a perspective view showing the fire door illustrated in Figure l, partly dismantled.

The appended drawings depict a fire door'constructed in accordance with this invention and which includes one form of smoke eliminator, this form of eliminator being shown by way of ex ample only.

In the drawings i represents the front wall of a Lancashire boiler, 2 the fire door opening in such wall, whilst the reference 3 generally indicates the fire door which is adapted to close the front end of the door 2 and swings from one end about a vertical hinge pin 4 arranged to one side of the door opening.

The reference 5 indicates the smoke eliminator or reducer and/or fuel economiser, herein referred to as a standard secondary air supply unit, and this unit is made in a standard size which is always substantially less in area than the door opening of any furnace on which the smoke eliminator is to be used, so that the smoke eliminator will readily fit more or less concentrically into the door opening with a perimetrical substantial marginal space around it; thus when the fire door is opened and closed there is no danger of the part of the smoke eliminator which protrudes into the furnace door opening fouling the peripheral walls of such opening.

This smoke eliminator is carried in a frame 6 which, together with the eliminator, completes the door. Whilst the eliminator is of a standard pattern, i. e. of standard shape and size (although it need not necessarily be of the form shown in the drawings), the frame 8 will vary in external shape and in size to suit the furnace to which the door is tobe fitted, thus rendering the standard eliminator suitable for affixing to that particular furnace, however much the external dimensions of the eliminator are smaller than those of the door opening of the furnace.

The frame 5 may be of any suitable perimetrical shape but will usualy conform in shape to the door opening of the furnace on which it is to be used and externally the vertical and horizontal dimensions of the frame 6 will be greater than the corresponding dimensions of the door opening.

The frame is provided with hinge lugs i at one end between which will be located a hinge lug ii affixed to the front plate of the furnace, and the latter lug will carry the hinge pin l passing through the lugs l.

The opposite end of the r frame 5 is provided with a suitable catch device 9 for holding the door in its closed position.

The frame 5 has an opening iii conforming in shape to a perimetrical flange I! on the smoke eliminator Pi and of the same dimensions a this flange, so that the latter will fit closely into the opening IS in the frame E.

Also on its. inner side the frame 6 is furnished with a flange l2 extending inwardly from the opening iii so as to form a rebate in which the flange H of the smoke eliminator can seat with the front face of the plate 13 of the eliminator 5 flush with the front surface Id of the frame 6.

Retaining plates l5, of which there may be four, as shown, are seated at their outer end in recesses it in the frame =6 and engage over the plate is of the eliminator 5 to lock the latter detachably in the frame 8, the plates [5 being secured to the frame 8 by studs ii.

The joint between the flange H of the eliminator and'the periphery of the opening it in the frame 6 may be sealed by any suitable sealing composition which is marked II in Figures 3 and 4.

The smoke eliminator shown in the drawings comprises a metal casting 18 consisting of the front plate 53, hereinbefore referred to, and furnished with a pair of horizontally spaced parallel inwardly directed air inlet nozzles l9 arranged at the upper part of the front plate, these nozzles being of frusto-conical form and outwardly flared at their outer ends 2%. In its'lowerpart the plate is is provided with a long horizontal rectangular opening 2 i, also adapted to-admit secondary air to the furnace, and this-opening 2! is adapted to be closed by an appropriately balanced door 22 hinged at 22 to a forwardly extending-part 24 of the said front plate is and, when in its closed position, extending upwardly and inwardly towards this plate which has a bead 25 against which the upper edge of the door is adapted to seat: the door also seats against forwardly extending approximately triangular side cheeks 26 provided on the plate it at the ends of the opening 2 i.

A hollow box-like cover 21 is'mounte'd on the rear or inner side of the plate 13 of the eliminator and is secured thereon by three bolts 23 passing through the plate i3 and screwing into internal lugs on the cover 2?, these bolts caarrying spacing sleeves 29 disposed between the nuts 30 of'the bolts and the front surface of the plate 1.3.

The cover 21 has openings 3| in its ends and is furnished with two large circular openings in its rear surface into which the nozzles l9 respectively project'so as to leave an annular space 32 around each nozzle between the latter and the cover 21. Thus, when the balanced door 22 is open air can pass inwardly through the opening 2i, through the hollow cover 21 (which together with the plate i3 forms a hollow box-like chamber) around the nozzles 19 and through the annular spaces 32 into the interior of the furnace above the fire bed of the latter.

The inner wall of the cover 21 may also be furnished with a series of holes 3? in addition to the openings 32 therein.

The nozzles i9 provide the normal secondary air and the opening 25 controlled by the balanced door 22 provides the additional secondary air that requires to be admitted to the furnace via the spaces 32 and holes 3! after firing the furmace and which additional air supply needs subsequently to be cut off when the fire is burning fully. The balanced door serves as a control valve and is hinged at the lower part of the opening 2| and so arranged that it opens under the action of gravity and inertia whenever the door is opened or shut; the equilibrium of the door 22 is such that it will fiy open if the opening movement of the fire door is suddenly arrested, or if the latter is rapidly closed, the valve or door 22 being subsequently manually closed at the appropriate time by the operator. I

The sleeves 29 and the bolts 28 carry a detachable and adjustable plate 33 which is adapted to cover the outer flared ends 29 of the nozzles I9, this plate preferably being adjustable on the sleeves 29 which may have notches 34 into which the plate 33 is adapted to engage to secure the plate detachably in any of a plurality, say three, adjusted positions, one of which preferably is a closed position in which the plate completely closes the outer ends of the nozzles IQ. Thus the plate covers the holes at all times sufficiently to protect the stokers eyes but, in addition, serves as a control valve for regulating and shutting off the supply of secondary air through the nozzles.

Finger pieces 35 may be provided on the plate to facilitate its adjustment or detachment and an air. inlet opening 36 may be provided to enable air freely to pass through the nozzles I9 when the plate 33 is spaced from the plate Hi.

The period for which the balanced door 22 is maintained open after stoking will depend upon the kind of coal that is being burned.

It will be seen that by this invention the cost of providing a smoke eliminator of a different size and shape for each different form of furnace door opening is avoided and that a standard eliminator can be provided for ranges of such door openings, the only special part required being the frame 6 into which the eliminator fits and which is a much simpler article to produce than the eliminator itself.

What I claim is:

1. A fire door for a furnace comprising in combination a frame having an aperture therein, a standard secondary air supply unit adapted to be located in the said aperture and to fit closely thereinto, retaining means for securing said unit on said frame and in said aperture therein; said unit comprising a casing including a front plate, a rear wall secured to said front plate and defining therewith a chamber, said rear wall being apertured for the passage of secondary air from said chamber into the furnace, and said rear wall including a lower portion extending forwardly beneath and in spaced relationship to said front plate and forwardly thereof to define therewith a front air inlet aperture to the interior of the said chamber, the plane of such air inlet being upwardly and rearwardly inclined, a plurality of spaced, axially parallel, air inlet nozzles carried by said front plate and directed rearwardly thereof toward said rear wall, said front plate having apertures therein with which said nozzles are in registration, and said rear wall having apertures therein with respect to which the rear ends of said nozzles are disposed in con centrically inwardly spaced relation to provide annular passage for air from the interior of said casing to the furnace, and a valve plate closing the front air inlet aperture defined by said front plate and the lower portion of said rear wall, the lower edge of said valve plate being hingedly mounted on said casing adjacent the lower edge of the front air inlet aperture, whereby said valve plate may open outwardly to uncover said aperture.

2. A fire door for a furnace comprising in combination an adaptor frame having an aperture therein, a secondary air supply unit adapted to be located in the said aperture and to fit closely thereinto, retaining means for securing said unit on the said frame and in said aperture therein; said unit comprising a casing including a front plate, a rear wall secured to said front plate and defining therewith a chamber, said rear wall being apertured for the passage of secondary air from said chamber into the furnace, and said rear wall including a lower portion extending forwardly beneath and in spaced relationship to said front plate and forwardly thereof to define therewith a front air inlet aperture to the interior of the said chamber, the plane of such air inlet being upwardly and rearwardly inclined, a plurality of spaced axially parallel air inlet nozzles carried by said front plate and directed rearwardly thereof toward said rear wall, said front plate having apertures therein with which said nozzles are in registration and said rear wall having apertures therein with respect to which the rear ends of said nozzles are disposed in concentrically inwardly spaced relation to provide annular passages for air from the interior of said casing to the furnace, a plate arranged in front of said nozzle apertures in the front plate, said plate being adjustable in an axial direction with respect to the said nozzles to control the ingress of air thereinto thereby to control at least partly the admission of secondary air to the furnace; and a valve plate closing the front air inlet aperture defined by said front plate and the lower portion of said rear wall, the lower edge of said valve plate being hingedly mounted on said casing adjacent the lower edge of the front air inlet aperture, whereby said valve plate may open outwardly to uncover said front air inlet aperture.

3. A fire door for a furnace comprising in combination a frame having an aperture therein, a standard secondary air supply unit, adapted to be located in the said aperture to fit closely thereinto, retaining means for securing said unit on the said frame and in said aperture therein; said unit comprising a casing including a front plate, a rear wall secured to said front plate and defining therewith a chamber, said rear wall being apertured for passage of secondary air from said chamber into the furnace, and said rear wall including a lower portion extending forwardly beneath and in spaced relationshi to said front plate and forwardly thereof to define therewith a front secondary air inlet aperture to the interior of the said chamber, the plane of such air inlet being upwardly and rearwardly inclined, a plurality of spaced axially parallel air inlet nozzles carried by said front plate and directed rearwardly thereof toward said rear wall, said front plate having apertures therein with which said nozzles are in registration, said rear wall having apertures therein with respect to which the rear ends of said nozzles are disposed in concentrically inwardly spaced relation to provide annular passages for secondary air from the interior of said casing to the furnace; and a flap closing the front air inlet aperture defined by said front plate and the lower portion of said wall, said flap being hinged at its lower part at opposite sides of the front inlet aperture and controlling admission of secondary air to said chamber and to furnace, said. flap being inclined to rest, in its aperture-closing position, with its upper edge against said front plate but bein adapted to swing downwards and forwards about its pivot to uncover the front-air inlet aperture. 4. A'fire door for a furnace according to claim .3 wherein aplate isarrangedin front of the said nozzle apertures in the front plate, said plate being adjustable in an axial direction with respect to the said nozzlesto control the ingress of airthereinto, thereby to control, at least partly, .the admission of secondary air to the furnace.

References Cited in the file of this .patent UNITED STATES PATENTS Number 5 418,074 545,967 748,326 381,166 1,275,339

Name Date Schue Dec, 24, 1889 Mills Sept. 10, 1895 Whitaker Dec. 29, 1903 Teller Mar. 10, 1908 West Aug. 13, 1918 Pelser Apr. 10, 1923 Craig Dec. 18, 1923 Robb Dec. 15, 1925 Earle Aug. 2, 1927 I-Iunker Nov. 3, 1936 Biegal Sept. 5, 1950 

